Soap Monitor not proxy-ing https?

Hi,
I have a webservice client that is written in Java and talks to a third party webservice.
The webservice sets behind https.

SOAPUI can get to the wsdl and send requests to the service no problem, however it appears that the monitor tool only proxies
http request as I get a 500 error when I try to proxy for the above webservice on https:

error:
java.io.IOException: Unable to tunnel through proxy

java settings:
-Dhttps.proxyHost=localhost -Dhttps.proxyPort=1975

the Monitor tool has its port set to 1975, and is listening on 127.0.0.1.

Any thoughts would be great